Scientists are taking a big step forward in the fight against the often fatal disease, malaria. They announced Wednesday that they've deciphered the genetic blueprint of the malaria parasite and the mosquito that spreads the disease. Researchers say the breakthroughs should hasten the development of a malaria vaccine and anti-malarial drugs.
An estimated 10 percent of the world's population is sickened each year by malaria, a disease, that kills up to three-million people annually, most of them children in sub-Saharan Africa.
Malaria is spread through the bite of a mosquito that is infected by a parasite known as Plasmodium falciparum. Because drugs to treat malaria and methods to keep the disease from spreading do not work very well, scientists decided six years ago to fight malaria by decoding the parasite's genetic blueprint.
It took an international team of 160 scientists in 10 countries less than one year of intensive work to achieve their goal - a map that identifies 96 percent of the genes, or proteins, that are responsible for the functioning of P. falciparum.
Researchers also decoded the blueprint for the mosquito that carries the parasite, a particularly aggressive insect drawn to humans called anopheles gambiae.
Dr. Anthony Fauci of the U.S. National Institutes of Health hailed the development. "On the one hand, it is an extraordinary accomplishment that is a landmark, and no one I think can deny that. But on the other hand, it is just the beginning, the beginning of opening the door to a new era of science in the study of malaria," he said.
Papers describing the sequencing of the parasite's genome appear jointly in the scientific journals Nature and Science.
Steven Hoffman, who is with the biotechnology firm, Senaria, is one of the co-authors of the article published in Science.
Dr. Hoffman says between 300-million and 900-million people will be stricken with malaria next year, and the tools for treatment are ancient. He points to the development of the main anti-malarial drugs - quinine, which isn't used any more due to drug resistance, chloroquine and a 2,000 year old Chinese herb derivative, artemisinin.
"The drugs that we use to treat the worst cases of malaria, for the most part, were introduced 400 to 2,000 years ago," said Dr. Hoffman. "For prevention, not that it doesn't work, which is primarily based on reducing contact with infected mosquitos, we use insecticide impregnated bed nets. That was the big advance of the 1990s."
This approach, Dr. Hoffman also says, is now becoming ineffective because mosquitos are developing resistance to the insecticides used in the bed nets.
But researchers may finally make giant steps in the war against malaria. That's because they now have at their disposal the genetic sequences of all three actors in the malaria disease cycle; the parasite, the mosquito and human beings.
"We can look at how we might genetically alter mosquitos so they might not admit the parasite," said Steve Hoffman of Senaria. "From the parasite, we have new targets of vaccines and targets of drugs. At the human genome side, what does it offer? Well, 23 million children are born every year in sub-Saharan Africa, but only one to three million of them die of malaria."
Based on the understanding of human genetics, Dr. Hunter went on to say it might become possible to determine which children are most likely to become infected with malaria and to vaccinate them.
Experts say humans have a weak immune response to the malaria parasite. But knowing the P. falciparum's genome might give researchers new targets to pursue in terms of developing a long-sought anti-malaria vaccine.
The first new anti-malarial drug is already being actively developed by German scientists based on the new genetics research.
Malcolm Gardner is co-author of three papers in Nature. Thanks to information Dr. Gardner and his colleagues posted on the internet, European researchers discovered an enzyme, or protein, found in the parasite but not in humans. The enzyme is very similar to a plant and bacterial enzyme that is easily destroyed with a compound.
"When they were tested it [the compound] in malaria parasites in culture, they killed the parasites, and they were also able to cure mice that were infected with malaria," said Mr. Gardner. "So, literally in the space of one year of having obtained the sequence information, investigators in Europe and Germany have identified this enzyme, have identified compounds which are now in pre-clinical, and perhaps clinical development."
But some malaria experts caution it still may be years before the advances of biotechnology translate into a useable malaria vaccine. The reason: the malaria parasite is a complicated organism that goes through a number of lifecycles inside its human host. In the words of one observer, that makes P. falciparum "a moving target."